If this is working, then great, but i wouldnt stay at such a low calorie count for too long. Yr body will go into starvation mode and you will find you wont be loosing as much, if anything at all in the long run.
My fitness pal is an online forum that'll sort out your daily calories. Its a great logging system.
Just thought this might help, and well done on such a great weight loss!!
Keep us posted x